With its announced launch of a whole-exome sequencing service for apparently healthy individuals, Ambry Genetics is the latest company to enter this growing market. But whether these services are useful for most people remains up for debate.

Murine neural tubes, with each image highlighting a different embryonic tissue type (blue). The neural tube itself (left) grows into the brain, spine, and nerves, while the mesoderm (middle) develops into other organs, and the ectoderm (right) forms skin, teeth, and hair.